In rotary machines such as steam turbines, seals are provided between rotating and stationary components. For example, in steam turbines, it is customary to employ a plurality of arcuate packing ring segments (bearing labyrinthian features) to form a labyrinth seal about and between stationary and rotating components. Typically, the arcuate packing ring segments are disposed in an annular groove in the stationary component concentric about the axis of rotation of the machine, and hence concentric to the sealing surface of the rotating component. The sealing function is achieved by creating turbulent flow of a working media, for example, steam, as it passes through the relatively tight clearances within the labyrinth defined by the seal face teeth and the opposing surface of the rotating component.
In order to avoid damage to the rotor and packing ring during transient conditions such as startup and shutdown, positive pressure, variable clearance packing rings are sometimes used. In positive pressure, variable clearance packing rings, the packing ring segments are typically spring biased into outer or large clearance positions causing the seal faces carried by the packing ring to be spaced substantially outwardly of the rotary component. After start-up, the working fluid medium, e.g., steam, is inlet to the grooves of the stationary component, urging the segments for move inwardly against the bias of the springs, toward the inner or small clearance positions. These springs are typically located within the annular groove defined by the stationary component, and are sized relative to the annular grooves in which they reside. In large turbine units, the annular groove is typically large enough to accommodate large springs having an elasticity capable of tolerating the pressure-force resulting from inlet of the fluid medium. In addition, the packing ring is typically large enough to allow springs to be affixed to the portion of the packing ring residing in the annular groove.
However, when working with smaller turbine units used in applications such as boiler feed pumps, reactor feed pumps, mechanical drives for compressors and pumps, and some generator drive units, it can become difficult and impractical to install capable springs within the narrow width/diameter annular grooves present in the smaller turbine unit. Thus, in these instances, there is a need for a springing device that can be used in conjunction with annular grooves having too small a width and diameter to accommodate conventional springs.